dont do the shirt and tie route. People will think your selling double glazing. I used to go out in a plain t-shirt, jeans and smart footwear.
Good luck
Funnily enough my son's canvasser has just changed from (smart) T shirt and jeans to shirt, tie, trousers and smart shoes, and his hit rate has soared!
He is canvassing a well to do area, and perhaps that is why?
maybe the attire of the canvasser shoudl reflect the area he is canvassing in?
Or it may just be coincedence of course, time will tell.
Just a thought.....